Stereotactic radiosurgery of residual or recurrent craniopharyngioma: New treatment concept using leksell gamma knife model C with automatic positioning system

Background/Aims: The present study analyzed the initial experience with the application of the original concept of 'robotic microradiosurgery' using Leksell Gamma Knife Model C with automatic positioning system for management of craniopharyngiomas. Methods: Eighteen patients with residual or recurrent craniopharyngiomas underwent radiosurgery with the use of multiple isocenters, mainly of smaller size, which were positioned compactly within the border of the lesion with resultant improved dose homogeneity, increased average dose within the target, and sharp dose fall outside the treated volume. Treatment planning was mainly guided by constructive interference in steady state images with and without gadolinium enhancement. Mean tumor volume was 1.8 cm³. In 12 cases the anterior visual pathways were either compressed or attached to the lesion. The average number of isocenters was 8.7 per cubic centimeter of target volume. Mean marginal irradiation dose was 11.6 Gy. Mean maximal dose to the anterior visual pathways was 8.4 Gy. Mean follow-up was 26.8 months, and median follow-up was 24 months. Results: Tumor growth was controlled in 17 cases (94%), and its volume reduction was attained in 13 cases (72%). In 3 patients significant shrinkage of the neoplasm after radiosurgery was accompanied by improvement of the visual functions. Their impairment was not marked in any case, nor was there any new endocrinopathy. Conclusion: Application of robotic microradiosurgery to the management of residual and recurrent craniopharyngiomas showed promising results during short- to intermediate-term follow-up, providing early tumor shrinkage in the majority of cases as well as sparing of visual and pituitary functions.